Pneumatic action for musical instruments.



1. A. OBST PNEUMATIC ACTION FOR MUSICAL INSTRUMENTS.

Patented Jan. 21, 1919.

APPLKCATION HLED SEPT. 10. 1914.

il i 7165,6635

JOSEPH A. OBST,

OF PAWTUCKET, RHODE ISLAND.

PNEUMATIC ACTION FOB MUSICAL INSTRUMENTS.

Application flied September 10, 18141.

T 0 all whom, it may concern:

Be it known that I, Josnrn A. Onsr, a citizen of the United States,residing at Pawtucket, in the county of Providence and State of RhodeIsland, have invented new and useful Improvement in Pneumatic Actionsfor Musical Instruments, of which the following, taken in connectionwith the accompanying drawings, is a specification.

The present invention relates to improvements in the construction andoperation of pneumatic actions for musical instruments. The presentconstruction particularly adapts itself to the employment of a singlevalve control for the motor pneumatic, in contradistinction to thedouble valve control orc inarily employed, and embodying primary andsecondary valves, but it is to be understood that while the invention isshown and described as a single valve act-ion, the prin ciples of thesame are equally applicable to the double valve action.

The object of my invention is to simplify the construction and lessenthe cost of devices of this character, and in particular, to increasethe responsiveness of such devices by improvements directed to thecontrol of the bleed devices thereof. Other and further objects willappear from the following description taken in connection with theaccompanying drawings, in which Figure 1 is a sectional view of a deviceembodying my invention.

Fig. 2 is a similar view showing the parts in different positions.

Fig. 3 is a fragmentary sectional view showing the parts in thepositions which they assume at one stage in the operation of the device,and

Fig. 1 is a cross section on the plane of the broken line 4 1, Fig. 1.

Like parts are indicated by like reference characters in the differentfigures.

The drawing illustrates a single motor pneumatic 1, the movable leaf ofwhich carries an arm 2 which is adapted to actuate the correspondingabstract, not shown, of a keyboard operated instrument in a manner wellunderstood and common to instruments of this class. The stationary leafof the pneumatic 1 is supported beneath a valve box 3, which has achannel 1, communicating by means of a tube 5 with a correspondingaperture in the tracker board of the instrument, not shown.

Each valve box 3 has a vacuum chamber 6,

Specification of Letters Patent.

Patented Jan. 21, 1919.

Serial No. 861,141.

in' constant communication, through a common passage 7, with anexhausting device, not shown, in the manner common to devices of thisclass. The vacuum chamber 6 of each valve box communicates with thechannel 1 of said box by means of a restricted passage 8, commonly knownas a bleed passage for the purpose of exhausting the air from channel 1into the vacuum chamber 6. Below the vacuum chamber 6 and separatedtherefrom by a flexible diaphragm 9, is a recess 10 with which thechannel 4 communicates.

The box 3 is formed with a chamber 11, which is in constantcommunication, by means of a channel 12 with the interior of the motorpneumatic 1. Said chamber 11 has a port 13 leading to the vacuum chamber6, and a port 14 leading to the atmosphere. A double faced valve 15 iscontained within the chamber 11 and adapted to control the two ports 13and 11 thereof. The valve 15 has a stem 16 extending through said port18 and preferably carrying on its end a disk 17, preferably disposedsomewhat above the upper surface of the diaphragm 9 in the normalcollapsed pos'tion of the latter, as shown in Fig. 1.

The saidfivalve 15, in the position shown in Fig. 1, wherein it rests bygravity on the bottom of chamber 11, closes the port 13 between saidchamber and the vacuum chamher 6, and leaves open the port 141, toestablish communication between the interior of the motor pneumatic land the atmosphere. In the position of the valve shown in Fig. 2,wherein it is shown as elevated by an air pressure beneath the diaphragm9, the valve shuts off the motor pneumatic from the atmosphere, andconnects it with the vacuum chamber 6.

My present invention relates to the bleed device by which the initialair pressure is sustained beneath the diaphragm 9, during the elevationof the valve 15, and by which the air pressure beneath the diaphragm isquickly reduced at the proper time to permit the fall of the valve 15after the motor pneumatic 1 has collapsed, and the chief object of myinvention is to render the apparatus more quickly responsive in itsaction.

The operation of my improved device is as 'follows:The normal positionof valve 15 is shown in Fig. 1, but when a perforation of the travelingnote sheet registers with the tracker-board aperture with which the tube5 is connected, the resulting impulse of air through the channel 4 fillsthe chamber 10 and lifts the diaphragm 9, .carrying it into contact withthe material surrounding the opening 18, and by its continued movementto lift the valve '15 to close the port 1i and open the port 13, asshown in Fig. 2, with the result that the diaphragm will substantiallyclose the end of the bleed passage 8 and restrict the flow of airthrough the bleed passage so the normal air pressure admitted to therecess 10 will be effective to raise the valve 15 into the positionshown in Fig. 2. The interior of the motor pneumatic l is thereby cutoff from the outer air and connected with the vacuum chamber 6,resulting in the collapse of the :movable leaf of the motor pneumaticand the operation of the corresponding (albstract the usual manner.

The closing of the bleed passage 8 -is not complete as a slight leakageofiair will occur around the opening 18, for the reason that 'thecontact of the diaphragm 9 with the material surrounding the opening :18is not sufficiently intimate to wholly prevent .a slight leakage of airinto the vacuum chamber 6. So long as the opening in .the trackerboardis uncovered *by the note sheet, this leakage is negligible, but whenthe opening in the tracker-board is closed, the air pressure in channeli and recess 10 becomes reduced sufiiciently to allow the diaphragm 9and valve 15 to'drop, thereby instantly openingthe .full :area of thebleed passage 8 to the vacuum chamber.

The responsiveness of the apparatus is greatly increased as theslackness of the dia phragm 9 substantially closes the bleed pas-p sagein advance of the lifting of the valve 15, restricting the bleedingeffect to :the slight leakage around the openinglS due to the imperfectcontact of the diaphragm withthe material around theopening I18, al-

though the .area 20, Fig. .4, .is preferablyslightly rounded in order toreduce theleakage to a minimum which, however, will be sufficient, 'dueto the .pull of :the vacuum chamber 6, to slightly reduce thepressure'in the recess 10, While the :perforation in rthe tracker-boardis closed. The closing :of Til-116 perforation in the tracker-board willtherefore be followed by the depression :of the diaphragm and theconsequent rapid i equalizationof the air pressure intllGIBCGSSIlOxfl-Ild the vacuum chainber6 vdue'to the complete openingofthe channels 4 and 8 which are of sufficient size to cause the pressurein the recess 10 to be instantly reduced to that of the chamber -6,rendering the apparatus extremely responsive to the opening and closingof the perforations in the tracker-board by the note sheet. In otherWords, the bleed aperture in my improved device is variable. Thepassages i and 8 are of suflicient area in cross section to efiect aninstantaneous change in the air pressure of recess 10, while thepassages 41: and 8 are restricted by the initial upward movement of thediaphragm so long .as the aperture in the tracker-board is open. Whenthe valve 15 is in its lowest position some space exists between thediaphragm 9-,and .thedisk 17, and theinitial elevation .ofxthe diaphragm.9 carries it into the positionshown'in Fig. 3, closing the opening18,before the-valve 15 is raised. In the positionshown in Fig. 3,, theair pressure in the recess 10 is substantially the normal air pressureso long as the corresponding perforation is .open, and :air is suppliedwfreely through :the flexible tube 5. Then the ,perforation intheitracker-Eboard is closed by the note sheet, the leakage from .theopening 18 reduces thegair pressure in the recess 10 sufficiently "toallow the *weight of the valve and the normal .air pressure upon itsupper surface :to :peel the diaphragm from the surface 20, and fullyopen the passage to the vacuum chamber.

:Lclaim,

In a pneumatic action for musical instruments,:a vacuum chamber, anairchamber, a flexible-diaphragmseparating said chainbers, an airchannel forsupplying airto said air chamber,,a bleed passage normallyopen between said air'channel and said vacuum chamber and entering saidvacuum chamber through a wall-of the vacuum chamber opposed to saiddiaphragm and lying in its path :as :said diaphragm is actuated by thedifference in air pressure on its opposite sides, a valve having itsstein in the path of said diaphragm with normally aspace be tween ;thewalve stem and the diaphragm, whereby the movement of the valve asactuated by theidiaphragm will occur subsequent to the covering of the.bleed passage by the diaphragm, .and th reverse :movement of the Valvewill occursubsequent to'iihe uncoveringiof the ibleed passage.

JOSEPH A. 01381. Witnesses:

GEORGE W. MILLER, vJosr-rn iB'OWLAND.

Copies of this patentimay be obtained forfive-icents' each, addressing[the .Gornniissionerzof Patents.

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